In recent years, several reports have underlined the increasing role of fungal infections as a cause of morbidity and mortality in hospitalised patients. For this reason, and also in light of the high mortality rate associated with these infections, chemoprophylaxis has been advocated by several authors. The available evidence suggests that both fluconazole and itraconazole are able to decrease candida colonisation and infection, when compared with placebo or with nonabsorbable antifungals. Data seem also to suggest that a decrease in fungus-related mortality can be achieved with prophylaxis, although with little effect on overall mortality, probably because of the importance of severe underlying diseases. Itraconazole proved to be effective in the prevention of fungal infections, including invasive aspergillosis, although with increased incidence of side-effects, often leading to treatment discontinuation. The other side of the coin is that antifungal prophylaxis might have untoward effects, such as the selection of triazole-resistant Candida strains or the induction of resistance. In addition, some authors have suggested that the use of triazoles might modulate the pattern of infecting organisms in cancer patients, increasing the risk of both aspergillosis and bacteremia. In conclusion, antifungal prophylaxis with triazole antifungals should be used with caution, only in patients at high risk for invasive fungal infections. These include allogeneic bone marrow transplant patients (especially those with mismatched or unrelated donors), acute myeloid leukaemia patients treated with high-dose cytarabine (C-ara), very-low-birth-weight infants, patients with chronic granulomatous disease, and high-risk surgical and intensive-care unit patients.